Percolation? Heat soak? Don't drive during summer??

Thanks for this! I'll see if I can figure some of this electrical out... electrical and me are not friends...
Well its time to change that.
There's plenty of basics about electrons and circuits including in the Chrysler Master Tech series to read and watch.

For now, you need to understand this.
Voltage is potential energy. Potential in that its there, ready and available.
Current is electrons moving.

The ammeter is showing approx 20 amps going to the battery.
upload_2020-9-23_13-47-7.png

If the battery is fully charged, current flow should look something like this.
upload_2020-9-23_13-44-2.png

The first things you need to do are:
* Check the battery condition. How you do this depends on the battery type. If you have a battery charger - try charging it on that. Again, depending on the charger this may also be a way of determining condition. Very crudely, you can check condition using a multimeter set to Volts DC on the battery. With nothing running, the battery should be at 12.8 Volts. If its higher, flip the lights on for a couple seconds to remove the surface charge. Remeasure. Another crude test is to start the car. While the starter is drawing current, the voltage should not drop below 9 or 10 Volts.
* While the car is running, measure the voltage at three places.
+ the battery. + the alternator output stud + close as possible to the voltage regulator input or sense terminal (ign).
Might have to do this twice. Once at slow idle and again at 1200 rpm or so.

If you drive at night, adding headlight relays will reduce the loads through the bulkhead connections and the relatively small headlight wiring on these cars.
Crackedback's harness is a good way to do it.
Bypassing the ammeter will leave you blind. Very rarely is there a problem in the ammeter - especially on a normal car.
IF the alternator output connection at the bulhead is damaged, then its better to install a parallel wire or copy the 'heavy duty' wiring arrangement sometimes also called 'fleet' or '60 - 65 amp' wiring. If you are using an AGM battery, its additionally important to monitor the charging rate because they do not disipate heat as rapidly as a traditional wet cell.